Anchoring pin and method for structures such as mine and tunnel roofs and side walls

ABSTRACT

An anchoring pin comprising an enlarged leading portion having a leading face for enlarging a smaller pre-drilled hole during longitudinal insertion of the pin therein, the pin body having a longitudinal bore which opens through its leading end for discharge of material broken-up and displaced by said leading portion during such enlargement of the hole. Also, an anchoring method comprising the steps of forming a hole in the structure to be anchored, providing a said anchoring pin having a leading portion of greater peripheral dimension than the formed hole, and inserting the pin into the hole to cause the pin leading portion to enlarge the hole while material displaced by such enlargement is discharged through the pin contained bore.

United States Patent 11 1 Banerjee et al.

1 1 ANCHORING PIN AND METHOD FOR STRUCTURES SUCH AS MINE AND TUNNELROOFS AND SIDE WALLS [75] Inventors: Bani R. Banerjee, Skillman;

Mukund D. Gangal, Plainshoro; Sigmund Black, Belle Mead all of [73]Assignce: Lee-Norse Company, Charleroi, Pa.

[22] Filed: Jan. 3, 1974 [21 Appl. No.: 430,407

1 Aug. 19, 1975 Williams 61/45 B Banerjee et a1 83/30 [57] ABSTRACT Ananchoring pin comprising an enlarged leading por tion having a leadingface for enlarging a smaller predrilled hole during longitudinalinsertion of the pin therein, the pin body having a longitudinal borewhich opens through its leading end for discharge of material broken-upand displaced by said leading portion during such enlargement of thehole. Also, an anchoring method comprising the steps of forming a holein the structure to be anchored, providing a said anchoring pin having aleading portion of greater peripheral dimension than the formed hole,and inserting the pin into the hole to cause the pin leading portion toenlarge the hole while material displaced by such enlargemcnt isdischarged through the pin contained bore.

5 Claims, 4 Drawing Figures ANCHORING PIN AND METHOD FOR STRUCTURES SUCHAS MINE AND TUNNEL ROOFS AND SIDE WALLS The present invention relates toanchoring pins and anchoring methods particularly adapted for anchoringstructures such as mine and tunnel roofs and side walls.

An object of the present invention is to provide a new and improvedanchoring pin particularly adapted for anchoring structures such as mineand tunnel roofs and side walls, which anchoring pin is both relativelyecconomical in construction and highly efficient in operation.

Another object of the invention is to provide a new and improvedanchoring pin of the type set forth which is of a design readilyadaptable for employment in structures of varying strengths.

Another object is to provide a new and improved anchoring pin of thetype set forth which is of a design permitting control of the forcerequired for insertion of the pin in the structures whereby suchrequisite insertion force may be minimized.

Another object is to provide a new and improved anchoring pin of thetype set forth which is particularly adapted to provide both suspensionsupport and compressed layer beam support of the anchored structures.

Another object is to provide a new and improved anchoring pin of thetype set forth which is particularly constructed and arranged to posesssignificant resistance to undesirable buckling and bending.

Another object is to provide a new and improved anchoring methodparticularly adapted for anchoring structures such as mine and tunnelroofs and side walls through the employment of such an anchoring pin.

Other objects and advantages of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingswherein, as will be understood, the preferred form of the invention hasbeen shown by way of illustration only.

In accordance with the invention, an anchoring pin for anchoringstructures such as mine and tunnel roofs and side walls may comprise abody having a leading end and a trailing end, said body adjacent itssaid leading end including a leading portion of peripheral dimensiongreater than that of a thereafter following portion of said body, saidleading portion having a leading face for displacing material to causeenlargement of a smaller pre-drilled hole during insertion of the pintherein, and said body having a longitudinal bore which opens throughits said leading end for discharge of material displaced by said leadingportion during such enlargement of the hole.

Also, in accordance with the invention, structures such as mine andtunnel roofs and side walls may be anchored by a method comprising thesteps of forming a hole in the structure to be anchored, providing ananchoring pin having an enlarged leading portion adjacent its leadingend of peripheral dimension greater than that of the formed hole andalso having a longitudinal bore which opens through its said leading endand inserting said anchoring pin into said formed hole to cause saidleading portion to enlarge said hole during said pin insertion whilematerial displaced by such enlargement is discharged through said pinbody contained bore.

Referring to the drawings:

FIG. 1 is a view in perspective illustrating one embodiment of anchoringpin constructed in accordance with the invention; and

FIGS. 2 through 4 are views diagramatically illustrating the anchoringof a mine or tunnel roof by the embodiment of anchoring pin shown inFIG. 1.

Referring more particularly to the drawings wherein similar referencecharacters designate corresponding parts throughout the several views,the illustrated anchoring pin 10 comprises an annular elongated steelbody 12 having a forward or leading end 14 and a rearward or trailingend 16. The body 12 contains an axial bore 18 which longitudinallyextends throughout the length of the body 12 and opens through the bodyleading and trailing ends 14, 16, respectively, the bore 18, ashereinafter described, serving for discharge of material broken-up anddisplaced during insertion of the pin 10 in the structure to beanchored. The body 12 is circumferentially imperforate and a completeannulus, that is, the body 12 contains no longitudinal slit or openingthrough its circumferential wall. The body 12 may be, for example, offrom one to six feet in length and is rigid, although sufficientlycapable of bending for employment in applications such as shallow seammining operations where the roof to be anchored may be lower than thelength of the body 12.

Adjacent to its leading end 14, the body 12 includes an integral,substantially enlarged, constant crosssection, annular leading portion20 of peripheral dimension P substantially greater than the peripheraldimension P of the immediately thereafter following intermediate orshank portion 22 of the body 12. It is believed that the outer diameterD, of the leading portion 20 should be at least one-thirty-second of aninch larger than the outer diameter D of the intermediate portion 22 andalso that such outer diameter D, should be at least onequarter of aninch, and even more preferably one-half of an inch to allow greater holetolerance, larger than the diameter D of the preformed hole 24 in whichthe pin 10 is to be installed. The leading portion 20 includes atransversely extending, annular leading face 26 which forms the leadingend 14 of the body 12, such leading face 26, as illustrated, extendingnormal to the axis of the body 12 and serving during the hereinafterdescribed pin installation for enlarging the smaller hole 24 to thelarger size of the leading portion 20. The length of the leading portion20 (that is, the dimension of the leading portion 20 longitudinally ofthe body 12) is only a minor portion of the length of the body 12 andvariable in different embodiments to maintain the force required for thepin installation at a minimum level while still providing the desiredanchoring. By way of specific example, a leading portion length of fourinches has been found to be adequate for developing up to twelvethousand pounds of pull-out force during testing of the described pin 10in concrete.

Moreover, for the anchoring of stronger structures, the length of theleading portion 20 could be appropriately reduced to correspondinglyreduce the required insertion force as high pull-out forces can beachieved in strong structures with a relatively short length of leadingportion 20.

At its trailing end 16, the body 12 includes an integral enlarged head28; and a supporting plate 30 is mounted peripherally around the bodyintermediate portion 22 for slidable movement longitudinally of the body12, the head 28 serving after installation of the pin 10 to maintain thesupporting plate 30 in supporting position adjacent to the outer surfaceof the structure being anchored.

The installation of the pin in a structure such as a mine or tunnel roof32 is schematically depicted in FIGS. 2 through 4. In such installation,a hole 24 of the beforedescribed diameter D (that is, a hole 24 ofdiameter substantially smaller than the diameter D of the pin leadingportion is first drilled in the roof 32 by a conventional drill bit 34rotatably driven through a drill steel 36. Then, the drill steel 36 andbit 34 are removed from the formed hole 24; and the pin 10 islongitudinally driven, leading end 14 first, into the hole 24 by aconventional push cylinder and/or impact driving means. As schematicallydepicted in FIG. 3, the pin 10 during its insertion is supported by asupport 38 and driven therethrough by, for example, a conventional roofdrill-and-bolter of the general type described in US. Pat. No.3,756,669, issued Sept. 4, 1973 and assigned to the assignee of thepresent invention. During such longitudinal insertion of the pin 10 intothe preformed hole 24, the leading face 26 of the pin leading portion 20compresses, crushes and displaces the rock adjacent the edges of thehole 24 to enlarge the latter to its diameter D,. The rock displaced bythe pin insertion is discharged longitudinally through the pin containedbore 18 and a communicating bore 40 in the support 48 to a suitableplace of discharge. The pin insertion causes the supporting plate to bedownwardly slidably moved along the pin intermediate portion 22; and,after the pin 10 has been fully longitudinally installed in the bore 24,the supporting plate 30 is, as shown in FIG. 4, affixed below the outeror lower level 42 of the roof 32 by the enlarged head 28. Hence, aftersuch installation, the supporting plate 30 provides suspension supportof the roof 32 while the leading portion 20 provides a strong elasticforce pressing against the wall of the now enlarged hole 24 forcompressed layer beam support of the roof 32. The pin 10 resultantlythereby provides a positive anchor for such roof 32.

From the preceding description, it will be seen that the inventionprovides a new and improved anchor pin and anchoring method foraccomplishing all of the beforestated objects and advantages. It will beunderstood however, that, although only a single embodiment of theinvention has been illustrated and hereinbefore specifically described,the invention is not limited merely to this single embodiment, butrather contemplates other embodiments and variations within the scope ofthe following claims.

Having thus described our invention, we claim:

1. An anchoring pin for anchoring structures such as mine and tunnelroofs and side walls, comprising an elongated body having a leading endand a trailing end,

said body adjacent its said leading end including a leading portion ofperipheral dimension greater than that of a thereafter following portionof said body, said leading portion being of outer diameter larger thanthe outer diameter of said following portion of said body, said leadingportion having an annular leading face extendingtransversely of the axisof said body capable of breaking-up and displacing material to causelateral enlargement of a smaller diameter hole during driven insertionof the pin, leading end first, therein, and said body having an axialbore which opens through its said leading and trailing ends fordischarge of material broken-up and displaced by said leading faceduring such pin driven insertion.

2. An anchoring pin according to claim 1, wherein said leading portionis of outer diameter at least oneeighth of an inch larger than the outerdiameter of said thereafter following portion of said body, said body isa complete annulus, said leading portion is, longitudinally of saidbody, only a minor portion of the length of said body, said leading faceextends normal to the axis of said body, and further comprisingsupporting plate means slidably carried by said body intermediate itsends.

3. A method for anchoring structures such as mine and tunnel roofs andside wall, comprising the steps of forming a hole in the structure to beanchored, providing an elongated annular anchoring pin including atransversely enlarged leading portion adjacent its leading end of outerdiameter substantially greater than the diameter of said formed hole andhaving a transversely extending annular leading face capable ofbreaking-up and displacing material to laterally enlarge a smallerdiameter hole, longitudinally driving said anchoring pin, leading endfirst, into said formed hole to cause said leading face of said leadingportion to break-up and displace material adjacent the edges of saidformed hole and thereby laterally enlarge said formed hole while saidpin is so driven therein, during such driving of said pin dischargingsaid broken-up and displaced material from the hole through an axialbore formed longitudinally through said anchoring pin, and employing theelastic force of the thus installed pin against the wall of the enlargedbore for anchoring the structure.

4. An anchoring method according to claim 3, wherein the provided pinincludes a leading portion of outer diameter at least one-quarter of aninch greater than the diameter of the formed hole.

5. An anchoring method according to claim 3, further comprising thesteps of, during said driving of said pin, causing a supporting plate toslide rearwardly on said anchoring pin, and employing said supportingplate, after the installation of said pin, for providing suspensionsupport of the structure.

1. An anchoring pin for anchoring structures such as mine and tunnelroofs and side walls, comprising an elongated body having a leading endand a trailing end, said body adjacent its said leading end including aleading portion of peripheral dimension greater than that of athereafter following portion of said body, said leading portion being ofouter diameter larger than the outer diameter of said following portionof said body, said leading portion having an annular leading faceextending transversely of the axis of said body capable of breaking-upand displacing material to cause lateral enlargement of a smallerdiameter hole during driven insertion of the pin, leading end first,therein, and said body having an axial bore which opens through its saidleading and trailing ends for discharge of material broken-up anddisplaced by said leading face during such pin driven insertion.
 2. Ananchoring pin according to claim 1, wherein said leading portion is ofouter diameter at least one-eighth of an inch larger than the outerdiameter of saiD thereafter following portion of said body, said body isa complete annulus, said leading portion is, longitudinally of saidbody, only a minor portion of the length of said body, said leading faceextends normal to the axis of said body, and further comprisingsupporting plate means slidably carried by said body intermediate itsends.
 3. A method for anchoring structures such as mine and tunnel roofsand side wall, comprising the steps of forming a hole in the structureto be anchored, providing an elongated annular anchoring pin including atransversely enlarged leading portion adjacent its leading end of outerdiameter substantially greater than the diameter of said formed hole andhaving a transversely extending annular leading face capable ofbreaking-up and displacing material to laterally enlarge a smallerdiameter hole, longitudinally driving said anchoring pin, leading endfirst, into said formed hole to cause said leading face of said leadingportion to break-up and displace material adjacent the edges of saidformed hole and thereby laterally enlarge said formed hole while saidpin is so driven therein, during such driving of said pin dischargingsaid broken-up and displaced material from the hole through an axialbore formed longitudinally through said anchoring pin, and employing theelastic force of the thus installed pin against the wall of the enlargedbore for anchoring the structure.
 4. An anchoring method according toclaim 3, wherein the provided pin includes a leading portion of outerdiameter at least one-quarter of an inch greater than the diameter ofthe formed hole.
 5. An anchoring method according to claim 3, furthercomprising the steps of, during said driving of said pin, causing asupporting plate to slide rearwardly on said anchoring pin, andemploying said supporting plate, after the installation of said pin, forproviding suspension support of the structure.